A constant supply of fast-flowing water may be obtained from evenly spread rainfall throughout the year Location must be a valley so that a dam can be formed. This can also provide a water supply as water can be stored in large reservoirs Bedrock must be stable and impermeable Lots of precipitation Initial costs are high so there must be a high demand to ensure profitability Easy ability to transport the energy

Must be narrow and deep Strong and impermeable rocks Large head of water Non-residential, space for hydro plant Lack of restrictions

Investment needed to build new power stations and dams, install turbines, pylons/cables needed for transport if electricity -but once up and running, the “natural, continual, renewable” flow of water makes its electricity cheaper than fossil fuels There are a lot of requirements for HEP to work and not many places fit these The plant needs to run at full capacity to be economic so need to be where there is high demand. Often are set up near aluminum smelters which use up the available energy Diagram: as you can see a lot of advanced technology and construction used so initial costs are very high

It is the most widely used renewable energy source, and despite the disadvantages and the many requirements it needs it can be slightly adapted in size. Many developing countries are using HEP on a small scale. Due to creation of reservoirs areas cleared and where new reservoirs drown vegetation the surrounding lakes can become more acidic and anaerobic Flood risk – if they overflow